This invention relates to torque-transmitting apply mechanisms and, more particularly, to thrust apply mechanisms incorporating ball ramp mechanisms.
A majority of prior art torque-transmitting mechanisms employ hydraulic apply systems wherein a fluid-operated piston is pressurized with hydraulic fluid to apply axial thrust to a plurality of friction discs thereby transmitting torque between two members of the torque-transmitting mechanism. These hydraulic systems require fluid passages to be formed in the transmission housing and requires a somewhat complicated valving mechanism to ensure the proper interaction of the hydraulic fluid with the devices to be controlled.
More recently, electromagnetic apply clutches have been suggested and viscous clutches have also been employed. A more recent event is the introduction of ball ramp or roller ramp apply mechanisms, which convert electric motor torque to axial thrust to establish the frictional engagement between adjacent torque-transmitting friction plates.
It is an object of the present invention to provide an improved torque-transmitting engagement mechanism.
In one aspect of the present invention, an electric motor torque is converted to an axial thrust, in a torque to thrust mechanism which in turn applies engagement force to a torque-transmitting mechanism.
In another aspect of the present invention, an electric motor supplies rotary torque to a ball and ramp system, which converts the rotary torque to an axial thrust force.
In yet another aspect of the present invention, the axial thrust force of the ball ramp system is initiated by a first ball ramp mechanism forcing frictional engagement between friction plates of a torque-transmitting mechanism.
In yet still another aspect of the present invention, axial movement of the initiating ball ramp also results in rotary movement of a second ball ramp, which in turn produces additional thrust on the torque-transmitting mechanisms to provide full engagement of the torque-transmitting mechanism.